Use pkgconfig for BuildRequires

https://fedoraproject.org/wiki/Packaging:PkgConfigBuildRequires

seahorse.spec

@@ -10,27 +10,23 @@ URL:            https://wiki.gnome.org/Apps/Seahorse
 #VCS: git:git://git.gnome.org/seahorse
 Source:         https://download.gnome.org/sources/%{name}/3.15/%{name}-%{version}.tar.xz
 
-BuildRequires:  glib2-devel
-BuildRequires:  gtk3-devel
-BuildRequires:  gcr-devel
+BuildRequires:  pkgconfig(avahi-client)
+BuildRequires:  pkgconfig(avahi-glib)
+BuildRequires:  pkgconfig(gio-2.0)
+BuildRequires:  pkgconfig(gck-1)
+BuildRequires:  pkgconfig(gcr-3)
+BuildRequires:  pkgconfig(gtk+-3.0)
+BuildRequires:  pkgconfig(libsecret-unstable)
+BuildRequires:  pkgconfig(libsoup-2.4)
 BuildRequires:  desktop-file-utils
 BuildRequires:  gettext
 BuildRequires:  gpgme-devel >= 1.0
 BuildRequires:  gnupg
 BuildRequires:  itstool
-BuildRequires:  libsoup-devel
-BuildRequires:  openldap-devel
-BuildRequires:  libnotify-devel
-BuildRequires:  openssh-clients
-BuildRequires:  libsecret-devel
-BuildRequires:  avahi-devel
-BuildRequires:  avahi-glib-devel
-BuildRequires:  intltool
-BuildRequires:  dbus-glib-devel
-BuildRequires:  gobject-introspection-devel >= 0.6.4
 BuildRequires:  libSM-devel
-# for g-ir-scanner
-BuildRequires:  libtool
+BuildRequires:  openldap-devel
+BuildRequires:  openssh-clients
+BuildRequires:  intltool
 BuildRequires:  vala
 
 # https://bugzilla.redhat.com/show_bug.cgi?id=474419
@@ -126,6 +122,7 @@ update-mime-database -n %{_datadir}/mime &> /dev/null || :
 - Update to 3.15.90
 - Update URL
 - Use license macro for COPYING and COPYING.LIB
+- Use pkgconfig for BuildRequires
 
 * Sat Feb 21 2015 Till Maas <opensource@till.name> - 3.14.0-4
 - Rebuilt for Fedora 23 Change